I thik that a World's Finest Beyond movie can be made as it is free from any other continuities.

Now, only if WB were smart enough to make a stand alone movie set in future, think World's Finest -Beyond, starring a older Batman and Superman, get Michael Keaton as Batman and Caviezel as Superman with young Terry Mc Ginns.

Hell, As it is a completely different continuity, they could even use Routh and Bale as older versions of Superman and Batman with added prosthetics and make up to make them look older.